[Elecraft] Displaying the keying waveshape on Spectrogram.

Fri Sep 12 10:43:00 2003

Hi Mike,

Actually, "in the pits" experience up- and down-wind of clicky signals
suggests that averaging (or adding up the power) does not track the
irritation and interference levels.

The only thing that happens when the clicker slows down is that there
is more "clear space" between clicks. This very firmly suggests that
"power in the sidebands" in a CLEAN sense vs. keying speed is NOT what
is causing the damage.

The fast attack slow decay AGC, and our eardrums, are responding to
the PEAK energy. The irritation occurs one sub-millisecond click at a
time.

Clicks do not sound softer because they are spread out. They actually
may get worse. I have heard a lot of signals on the air (rig unknown)
which have a vastly (10 db?) accentuated leading click at the
beginning of a word, which suggests power supply charge-up issues.
This last is also easily visible if one uses the "Scroll 1" or "Scroll
2" waterfall displays which will display the leading click as quite
broader than the others.

As the most elegant counter to the keying-speed-as-villain theories,
W1AW can send code practice at 35 WPM and there is NOTHING to be heard
beyond +/- 250 Hz.

A clicky transmitter on the other hand, creates the "click" in a very
short interval, MUCH shorter than the space between dits at 35 wpm.

Wayne described the K2 clicks as derived from the RC curve intercept
portion of a 3 or 4 ms state change. That means the energy is being
created in LESS THAN A MILLISECOND, on EVERY state transition. It is
NOT related to keying speed. It was NOT found to be related to keying
speed on the clicky MP either.

That means to measure clicks, you need to detect PEAK click energy,
anywhere, anytime it occurs. Spectrogram does this for you nicely in
software with the "PEAK HOLD" function.

Also, since program has a "sweep frequency", and since the click is
very short duration, the peak energy of the click can be maxing out at
one frequency while the program is looking at another. This in turn
requires varying the keying speed while the program is logging the
peaks, so peak energy does not get "missed".

Varying the keying speed back and forth until the red curve quits
increasing takes care of this problem. (The red curve is the
collection of peak maxima at each sampling frequency, occurring so
long as the PEAK HOLD function is on.)

Any wonder Yaesu figures they can get away with doing nothing when
they see our own lack of unity and precision on the issues?

Thank God for SOME manufacturers with principles. (Keep smiling,
Wayne, you guys are accomplishing more than you know...)

73, Guy

----- Original Message ----- 
From: "Mike S" <[email protected]>
To: <[email protected]>
Sent: Friday, September 12, 2003 8:26 AM
Subject: Re: [Elecraft] Re: Displaying the keying waveshape on
Spectrogram.

> At 12:08 AM 9/12/2003 -0400, Dale Boresz wrote...
> >After reading Guy's (K2AV) excellent explanation of measuring the
K2's keying waveform with Spectrogram, I decided to measure my own K2,
using the ICOM IC-746PRO as the monitoring receiver.
> >
> >The Spectrogram plot of the results can be viewed at:
> >http://64.105.107.250/kqrv/k2keying.aspx
>
> Without the keying speed being specified, the results aren't very
meaningful. The amount of energy in the sidebands will vary with
keying speed.
>
> Mike
> W8UR
>
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